Which one is not a correct statement?

Options

A. Primary pollutants are those which are emitted directly from the source
B. Acid rain is primary pollutant
C. Particulates refer to all atmospheric substances that are not gases
D. All of these

Answer

To determine which statement is not correct regarding pollutants, we will analyze each option provided in the question step by step.

### Step 1: Analyze the first statement
**Statement:** Primary pollutants are those which are emitted directly from the source.

**Analysis:** This statement is correct. Primary pollutants are indeed substances that are released directly into the atmosphere from sources such as factories, vehicles, and other industrial processes. Examples include carbon monoxide, sulfur dioxide, and particulate matter.

### Step 2: Analyze the second statement
**Statement:** Acid rain is a primary pollutant.

**Analysis:** This statement is incorrect. Acid rain is not a primary pollutant; it is classified as a secondary pollutant. Acid rain forms when primary pollutants, such as sulfur dioxide and nitrogen oxides, react with water vapor in the atmosphere to produce sulfuric and nitric acids. Therefore, this statement is false.

### Step 3: Analyze the third statement
**Statement:** Particulates refer to all atmospheric substances that are not gases.

**Analysis:** This statement is correct. Particulates include solid or liquid particles suspended in the air, such as dust, soot, and liquid droplets. They are not gases, making this statement accurate.

### Step 4: Analyze the fourth statement
**Statement:** All of this.

**Analysis:** This statement suggests that all previous statements are correct. Since we have identified that the second statement is incorrect, this statement is also incorrect.

### Conclusion
The statement that is not correct is: **"Acid rain is a primary pollutant."**

### Summary of the Solution
1. The first statement about primary pollutants is correct.
2. The second statement about acid rain being a primary pollutant is incorrect (it is a secondary pollutant).
3. The third statement about particulates is correct.
4. The fourth statement claiming all are correct is also incorrect due to the second statement.

### Final Answer
The incorrect statement is: **"Acid rain is a primary pollutant."**

---